Fluid actuated vibrator devices



' Feb. 4, 1969 D. E. BICK 3,425,498

FLUID ACTUATED VIBRATOR DEVICES Filed Nov. 10, 1966 INVENTOR Jam m E- KICK 3km, 1W4

ATTORNEY United States Patent 49,304/ 65 U.S. Cl. 173-52 Int. Cl. F011 15/04; E01g 3/04; E21b 1/00 7 Claims ABSTRACT OF THE DISCLOSURE A percussive tool has parallel cylinders in which pistons perform their working strokes alternately under the control of a main valve. Each piston opens a pilot valve during the first part of the working stroke through which the flow of hydraulic fluid causes the other piston to retract, the speed of retraction being reduced by means of a restrictor, while the completion of retraction movement of said other piston closes the associated pilot valve, whereupon the pressure of fluid then trapped in the end of the cylinder causes the main valve to move from one operative position to the other.

This invention relates to fluid-actuated vibrator devices suitable for use with percussive tools.

According to the invention, a vibrator device suitable for use with a percussive tool comprises two cylinders each of which contains a double-acting reciprocable piston, a main valve having two operative positions in one of which one of the pistons is caused by fluid pressure to perform a working stroke and in the other of which the other piston is caused by fluid pressure to perform a working stroke, and a pilot valve associated with each cylinder and piston, each of said pilot valves being arranged to be opened by movement of the piston during its working stroke, to cause the other piston to perform its return stroke under fluid pressure, and being arranged to be closed by movement of the piston during its return stroke, movement of the piston on its return stroke after closure of its pilot valve causing movement of the main valve from one operative position to the other operative position.

It may be arranged that each pilot valve is opened early in the working stroke of the piston, whereby the other piston performs its return or nonworking stroke and then closes its associated pilot valve towards the end of the return stroke, whereby the main valve changes from one operative position to the other. The operation of the main valve is thus independent of the length of the working stroke of each piston, so that the mechanism may not be stalled by limitation of piston movement under excessive working load. Moreover, the energy required for operation of the main valve is taken only on the return stroke of each piston.

According to a further feature of the invention the fluid displaced by movement of each piston on its return stroke flows through restrictor means which causes the return stroke to take longer time than the working stroke. The restrictor means reduces the kinetic energy of each piston on its return stroke, and it moreover provides a means whereby the operating frequency of the percussive tool may be varied.

One embodiment of the invention is illustrated in the accompanying partly sectional diagrammatic drawing.

A body 1 is formed with two parallel cylinder bores 2, 102 in side by side relationship. A piston 4 slidable in the bore 2 has a piston rod 5 extending through a bearing 6 and a sealing ring 7 at one end of the bore, and

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a tail rod 8 of equal cross-section extending through a bearing 9 and a sealing ring 11 at the other end of the bore. The piston 4 is formed with a snubbing slot 10 which extends from its end face adjacent the piston rod 5. The piston 4 separates a chamber 12 into which a fluid supply port 13 opens, from a chamber 14 into which a fluid return port 15 opens. A pilot valve is formed by a cylinder port 16 with which the piston cooperates, the cylinder port 16 being adjacent to but axially spaced from the supply port 13.

The tail rod 8 operates in a chamber 17 which has a vent 18. The piston rod 5 extends with clearance through an open counterbore 19 in the body 1, and it can strike an anvil member 21 which is slidable in the bore 22 of an anvil housing 23. This housing 23 is slidably mounted on parallel tie rods 24, 25 which have their ends fixed in the body 1. The other ends of the tie rods 24, 25 are fixed by nuts 26 to the flange 27 of a pick housing 28, while springs 29 which encircle the tie rods, urge the anvil housing 23 against the body 1. The spring 29 cushions the impact of the head of the anvil member 21 against the end of the bore 22 in the housing 23.

The pick housing 28 provides a guideway 32 for the shank 33 of a pick 34. The pick 34 is resiliently urged towards the work by a pair of caged spring devices 35 which are slidably located in a second flange 36 of the pick housing 28. Outward movement of the pick under spring load is limited by a head 37 on the shank 33. The provision of the anvils ensures that there is no side load on the pistons if the work force on the picks is offset from the axis of the pistons.

A similar piston, anvil and pick assembly is carried by the other side of the body 1, and like elements of the assembly are indicated by reference numerals which are increased by 100.

Fluid pressure for operation of the percussive tool is supplied to a connection 41 and through a starting valve 42 to two pressure ports 43, 44 of a spool type main valve. A return connection 45 leads to a return port 46. A service port 47 is disposed between the pressure port 43 and the return port 46, While a second service port 48 is disposed between the pressure port 44 and the return port 46. A valve spool 49 is formed with one land 51 which, in the central position, just closes the ports 43 and 47, and another land 52 which just closes the ports 44 and 48. A biassing spring 53 urges the valve spool 49 to one operative position in which the pressure port 44 is open to the fluid supply port 113. In the other operative position of the valve spool the pressure port 43 is open to the fluid supply port 13. The service port 47 is connected to the fluid return port by a passage 54, while the service port 48 is connected to the fluid return port 15 by a passage 55. In the position of the spool 49 as shown, the port 115 is open by way of the passage 54 and the service port 47 to the low pressure in the return port 46 and the connection 45, while return port 15, passage 55 and service port 48 are closed from the connection 45 by the valve spool land 52. In the other operative position of the spool 49, the land 51 closes the service port 47, while the land 52 opens the service port 48.

The cylinder port 16 is connected to the passage 54 through an adjustable restrictor 56 and the cylinder port 116 is connected to the passage 55 through an adjustable restrictor 57. The adjustable restrictors 56, 57 together constitute restrictor means whose purpose will be described.

An operating cycle during continuous running will be described. With the valve spool 49 in the position shown, fluid under pressure at the connection 41 communicates with the port 44, and past the valve spool land 52 and the fluid supply port 113 to the chamber 112. The piston 104 has been moving downwardly on its working stroke and has just closed the chamber 114 from the fluid return port 115, passage 54, the main valve ports 47 and 46, and the return connection 45, except for the restricted flow connection provided by the snubbing slot 110. The latter provides hydraulic damping which cushions the ultimate downward movement of the piston 104 if it is not arrested earlier by reaction of the work load.

While the piston 104 has been moving downwardly past the cylinder port 115, fluid under pressure has had access through the latter, the restrictor 57 the passage 55 and the port to the chamber 14, while the chamber 12 has been open through the port 16, restrictor 57, passage 54 and the main valve ports 47, 46 to the return connection 45. The piston 4 has therefore been moving on its return stroke, but at a slower rate than the movement of the piston 104 on its working stroke because the flow of fluid entering the chamber 14 and leaving the chamber 12 is restricted by the restrictor 57 and 56 respectively. The piston 4 has just closed the cylinder port 16 whereby fluid in the chamber 12 is trapped and increased in pressure due to the inertia of the piston 4 until the supply pressure is exceeded, at which point, the pressure in the chamber 12 acting on the end of the spool 49 moves the valve spool 49 to its other operative position.

The land 51 then opens the pressure port 43 to the chamber 12 whereby supply pressure is maintained on the area at that end of the spool, while the land 52 closes the pressure port 44 but opens the return port 46 to the passage 55. Both the chambers 14 and 112 are then at the low fluid pressure of the return connection 45, and also the area at the end of the spool 49 adjacent the port 113. The valve spool 49 is thus maintained in said other operative position by fluid pressure whereby the piston 4 is moved on its working stroke by fluid pressure. When the piston 4 uncovers the cylinder port 16, fluid is admitted by way of the restrictor 56 and the passage 54 to the chamber 114, while fluid can leave the chamber 112 by way of the cylinder port 116, the restrictor 57 and the passage 55. Thus, while the piston 4 continues on its working stroke, the piston 104- commences its return stroke though at a slower rate in view of the flow to and from the latter through the restrictors 56 and 57. The piston 4 completes its working stroke, and it waits while the piston 104 completes its return stroke.

When the piston 104 closes the cylinder port 116, the surge of pressure due to trapped fluid in the chamber 112 moves the valve spool 53 to the operative position shown in the drawing, whereupon the piston 104 commences another Working stroke.

The setting of the restrictors 56, 57 may be varied together to vary the time taken for the return stroke, and thus to vary the working frequency of the percussive tool. A similar controlling effect can be achieved by provising one restrictor only in either of the positions shown. The restrictor means moreover reduces the kinetic energy of each piston on its return stroke.

After stopping, the pistons 4, 104 may be in the wrong positions for starting. This can be corrected by the starting valve 42 which is turned to close the port 43 from fluid pressure, and instead to admit pressure through a non-re turn valve 58 to the supply port 13 and the chamber 12. This pressure also moves the valve spool 53 to its other operative position whereupon the piston 4 will travel down the bore 2, while the piston 104 will travel up the bore 102. A fixed restrictor 59 of high resistance to flow between the supply port 113 and the cylinder port 116 provides a low pressure escape for fluid from the chamber 112, whereby the piston 104 is enabled to complete its return stroke fully. Upon returning the starting valve 49 to the position shown, the supply of fluid pressure to the non-return valve 58 is cut off before the supply to the ports 43 and 41 is opened, so that biassing spring 53 moves the valve spool 49 to the position shown, whereby fluid pressure is admitted to the supply port 113. The pistons 104 and 4 will then reciprocate as described.

It is arranged that each piston moves through part of its working stroke to acquire kinetic energy before striking the anvil 21 or 121 as the case may be, and the impact is transmitted to the pick 34 or 134 respectively. At the end of the working stroke each anvil is arrested by engagement of its head with the end of the bore 22 or 122 in the housing 23 or 123, as the case may be. This arrested movement is cushioned by the spring 29 or 129.

In the absence of work pressure against the picks 34, 134 these are urged away from their housings 28, 128 by the spring devices 35, 135, to positions in which the heads 37, 137 engage the pick housings 28, 128. The anvils 21, 121 are not then displaced by the picks 34 and 134 from the ends of the bores 22, 122 but they will receive any residual energy of the pistons which is not dissipated through the snubbing slots 10, 11.0. This residual energy is absorbed by movement of the anvil housings 23, 123 against the load of the springs 29, 129.

The percussive tool may be used in a generally horizontal position whereby the spring devices 35, 135 urge the picks away from their housings, but if the tool is adapted for use in a generally upright position, the spring devices may be omitted since the picks can drop if the tool is lifted away from the work.

In one application, two or more percussive tools as described may be mounted adjacent the lower edge of an excavator bucket with the several picks arranged in line with said edge.

I claim as my invention:

1. A vibrator device suitable for use with a precussive tool comprising (A) two cylinders each of which contain a doubleacting reciprocable piston, each cylinder having (1) a fluid supply port at that end portion of the cylinder to which the supply of fluid under pressure causes the piston to perform a working stroke, and

(2) a fluid return port at the other end portion of the cylinder,

(B) a main valve having two operative positions in one of which the fluid supply port of one cylinder is connected to a fluid pressure supply passage and the fluid return port is connected to a fluid return passage, and

in the other of which the fluid supply port of the I other cylinder is connected to the fluid pressure supply passage and the fluid return port is connected to the fluid return passage,

(C) a pilot valve associated with each cylinder and piston and including a cylinder port which is axially spaced from the fluid supply port so that it is opened by the piston during the first part of its working stroke and subsequently closed towards the end of the return stroke, the cylinder port of one cylinder being connected to the fluid return port of the other cylinder and the cylinder port of the other cylinder being connected to the fluid return port of the one cylinder, whereby the return stroke of each piston is accomplished by the flow of pressure fluid from the cylinder in which the other piston is slidable through the cylinder port to the return flow port of the one cylinder, and by return flow from the one cylinder through the cylinder port and through the main valve to the fluid return passage, and

(D) a restrictor interposed in at least one of the connections between each cylinder port and the fluid return port which causes the return stroke of each piston to take longer time than the working stroke, the movement of each piston on its return stroke after closure of its pilot valve causing movement of the main valve from one operative position to the other operative position.

2. A vibrator device according to claim 1, wherein the main valve comprises a movable spool having areas on its opposite end portions which are exposed to fluid pressure in the respective supply ports.

3. A vibrator device according to claim 1, wherein each return port is spaced from one end of the cylinder, while a hydraulic snubbing device is operable between the piston and the return port to cushion the ultimate movement of the piston towards said end of the cylinder.

4. A percussive tool having a vibrator device according to claim 3, wherein each piston on its working stroke acts through a separate movable anvil member to drive a pick, the anvil member having a mounting which includes spring means arranged to absorb any residual energy transmitted by the piston at the end of its Working stroke to the anvil member.

5. A percussive tool according to claim 4, wherein each pick has a mounting which includes a further spring means urging the pick out of range of the anvil member, but being yieldable under pressure of the work against the pick to bring the latter into the actuation range of the anvil member.

6. A vibrator device for use with a precussive tool comprising (A) two cylinders in each of which a double-acting piston is slidable,

(B) a main valve adapted in one operative position to connect a fluid pressure supply passage and a fluid return passage to opposite end portions respectively of one cylinder, and in another operative position to connect the fluid pressure supply passage and the fluid return passage to opposite end portions respectively of the other cylinder, whereby the piston in the cylinder 50 connected is operable by fluid pressure on its working stroke, and

(C) passage means including pilot valve means associated with each cylinder and piston, adapted by said main valve selectively to connect the fluid return passage and the fluid pressure supply passage to opposite end portions respectively of one or other of the two cylinders, each pilot valve being opened by the piston with which it is associated during the first part of the working stroke of the piston whereby the other piston commences its return stroke, and said other piston acting towards the end of its return stroke to close the associated pilot valve, the main valve being responsive to closure of each pilot valve whereby it is movable from one operative position to the other.

7. A vibrator device according to claim 6, wherein the passage means includes restrictor means which causes each piston to move at lower speed on its return stroke than the speed of the working stroke.

References Cited UNITED STATES PATENTS 279,984 6/1883 Sharpneck 91-191 2,643,644 6/1953 Way 91-135 2,866,415- 12/1958 Montelius 91191 2,996,014 8/1961 Lee 91-191 FOREIGN PATENTS D. 18,115 10/1956 Germany.

PAUL E. MASLOUSKY, Primary Examiner.

US. Cl. X.R. 

